JP2010031858A - Regenerating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a regenerating device capable of regenerating a particulate filter in any operating condition. <P>SOLUTION: This regenerating device relates to a regenerating device for a particulate filter 11 in an exhaust system comprising an exhaust duct 13 and a catalyst 15 assembled in the exhaust duct 13 on an upstream side of the particulate filter 11. The exhaust system or a combustion engine is provided with an injection device 17 communicated with a fuel reservoir to supply fuel, especially hydrocarbon included fuel, to a flow of exhaust gas. The regenerating device includes a burner 19 and at least one switching device 21. The burner 19 can heat the catalyst 15 to a reaction temperature, in which heating reaction of the fuel occurs. The switching device 21 selectively switches the burner 19 and the injection device 17 between operation and non-operation according to an operating condition of the exhaust system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a particulate filter regenerator in an exhaust system, and the exhaust system includes an exhaust duct for guiding high-temperature exhaust gas from a combustion engine, particularly a diesel engine, and the exhaust duct upstream of the particulate filter. The exhaust system or combustion engine is provided with an injection device that communicates with the fuel reservoir and can supply the fuel, particularly hydrocarbon-containing fuel, to the exhaust gas flow. Yes.

  The exhaust gas discharged from the combustion engine into the atmosphere contains various pollutants. In order to reduce pollutant emissions, various devices have been developed to post-process the exhaust gas. For example, a catalyst is used to convert harmful gaseous substances into innocuous components, and a particulate filter is used to trap unwanted solid particles. In the exhaust system of a diesel engine, for example, an oxidation catalyst for diesel and a particulate filter disposed downstream thereof can be provided. Soot-like fine particles (soot) contained in the exhaust gas flow are collected by a particulate filter and stored therein. When the amount reaches a predetermined amount, it is necessary to remove the collected soot from the particulate filter so that the exhaust gas is not excessively hindered. This process is called reproduction. A general process for regenerating the particulate filter is to heat the particulate filter to a predetermined temperature in order to incinerate the accumulated soot. This can basically be performed by a desired heating device. However, this heating device needs to have a relatively high performance in order to heat the particulate filter to the ignition temperature of the soot, and therefore requires a large amount of energy and a large installation space.

  Therefore, other processing methods based on the principle of secondary fuel injection (HC supply) have been developed. This takes advantage of the fact that fuels, particularly in the form of unburned hydrocarbons, can cause a reaction in the catalyst and heat the catalyst. Above a specific temperature commonly referred to as the light-off (ignition) temperature, an exothermic reaction of the fuel occurs, that is, the reaction continues autonomously after ignition and continues to release heat. By this exothermic reaction, the catalyst can be heated to a degree sufficient to heat the particulate filter disposed downstream to the temperature required for incineration of the deposited soot. In this case, another heating device is unnecessary. Injection of fuel into the exhaust gas stream is usually done using an injection device placed in close proximity to the catalyst. Alternatively, the fuel can be injected into the exhaust gas flow inside the engine, for example by post-injection of fuel into the combustion space.

  However, since the exothermic reaction does not occur when the catalyst temperature is lower than the light-off temperature, regeneration of the particulate filter by fuel injection is possible only when the combustion engine is in a specific operating state. Furthermore, there is a problem that fuel consumption increases.

  Accordingly, it is an object of the present invention to enable the regeneration of the particulate filter to be more flexible, more reliable, and save more fuel.

  The above-mentioned problem is solved by a reproducing apparatus having the features of claim 1.

  According to the present invention, the regenerator further includes a burner capable of heating the catalyst to a reaction temperature at which an exothermic reaction of the injected fuel occurs, and the burner and the burner according to the operating state of the exhaust system and / or the combustion engine. And at least one switching device that selectively switches the injection device between activated and deactivated.

  The catalyst can be heated to the light-off temperature at any time using a burner, and regeneration can be performed regardless of the operating state of the combustion engine. In the present invention, the burner only needs to be able to heat the catalyst to the reaction temperature, and in this respect, the particulate filter is designed to be substantially smaller and less energy consuming than the burner that directly heats the particulate filter. be able to. Since the above reaction temperature is usually lower than the incineration temperature of the deposited soot-like fine particles, significant savings are possible. Depending on the operating conditions of the exhaust system and / or the combustion engine, the switching device can be operated by selecting one or both of the devices, which optimizes the operation of the regenerator as a whole. The

  The present invention further relates to a method for regenerating a particulate filter of an exhaust system, the exhaust system including an exhaust duct for guiding a high-temperature exhaust gas flow from a combustion engine, particularly a diesel engine, and the upstream side of the particulate filter. An injection device comprising a catalyst, in particular an oxidation catalyst, incorporated in an exhaust duct and capable of supplying the exhaust system or the combustion engine with fuel, in particular a hydrocarbon-containing fuel, into an exhaust gas stream in communication with a fuel reservoir Is provided.

  The method according to the present invention further includes a step of providing a burner capable of heating the catalyst to a reaction temperature at which an exothermic reaction of fuel occurs, a step of determining an operating state of the exhaust system and / or the combustion engine, and the particulate A step of operating the burner and / or the injection device according to the determined operating state when the filter is regenerated.

  Further developments of the invention are described in the dependent claims, the detailed description of the invention and the drawings.

  The switching device is preferably configured to operate the burner when the temperature of the catalyst is lower than the reaction temperature and the particulate filter needs to be regenerated and, if necessary, the injection device. Therefore, for example, the accumulation of soot-like fine particles in the particulate filter has reached a certain level that needs to be regenerated, but on the other hand, the catalyst temperature causes an exothermic reaction, for example, immediately after the start of the combustion engine. If it is too low, the switching device activates the burner, which allows the catalyst to be heated efficiently and quickly to the temperature required for secondary fuel injection. In addition, the injector operates except when sufficient fuel that has not been consumed is already included in the exhaust gas stream.

  The switching device is preferably configured to operate only the injection device when the temperature of the catalyst is higher than the reaction temperature and regeneration of the particulate filter is necessary. Thus, as long as excessive operation of the burner is avoided and secondary fuel injection is possible, regeneration of the particulate filter is efficiently performed by this secondary fuel injection.

  The switching device can also be configured to deactivate the burner again when the catalyst temperature becomes higher than the reaction temperature. Therefore, for a more efficient heating method, switching occurs as soon as the catalyst reaches the required temperature. Depending on the mode of application, it may be desirable to operate the burner with the injector for a predetermined time after reaching the reaction temperature or until a predetermined threshold temperature is reached.

  The regenerator can be configured as a modular unit and the injection device can be integrated into the modular unit. Such a configuration makes it possible to install the regenerator in the exhaust system of various types of combustion engines, and is advantageous in terms of manufacturing and maintenance.

  Burners and injectors can be realized by common components that can be easily integrated into many different exhaust systems.

  The object of the invention is further solved by an exhaust system according to claim 8.

  In the regeneration method according to the present invention, the catalyst temperature can be measured using, for example, a temperature sensor attached to the catalyst in order to determine the operating state of the exhaust system. Alternatively, the operating parameters of the combustion engine, such as its temperature and speed, may be determined.

  The burner preferably operates when the temperature of the catalyst is below the reaction temperature and the particulate filter needs to be regenerated. On the other hand, if the temperature of the catalyst is higher than the regeneration temperature and regeneration of the particulate filter is necessary, preferably only the injection device is operated. The burner can be deactivated when the catalyst temperature rises above the reaction temperature.

The figure which shows schematically a part of exhaust system provided with the particulate filter, the oxidation catalyst, and the regeneration device according to the present invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  The exhaust duct 13 shown in the drawing receives a high-temperature exhaust gas flow from a combustion engine (not shown) at one end on the upstream side, guides it to an exhaust tail pipe (not shown), and passes through the exhaust tail pipe in the atmosphere. Exhaust the exhaust gas. Before diffusing into the atmosphere, the exhaust gas stream passes through the catalyst 15 and the particulate filter 11 for emission control as indicated by the arrows. The catalyst 15 may be a general oxidation catalyst such as a diesel oxidation catalyst. The particulate filter 11 is a filter for soot-like fine particles, and filters soot-like fine particles contained in the exhaust gas flow from the exhaust gas flow and stores them inside. The regenerator is disposed upstream of the catalyst 15, and here is configured as a modular apparatus, that is, a regenerator module 23. The regeneration module 23 includes both the injection device 17 and the burner 19, both of which communicate with the exhaust duct 13. The injection device 17 is further connected to a fuel reservoir (not shown). As for the connection relationship between the regeneration module 23 and the exhaust duct 13, on the one hand, the injection device 17 is opened in the exhaust duct 13, and on the other hand, the burner 19 has a sufficient heat transfer relationship with the catalyst 15. ,It is configured.

  The regeneration module 23 is applicable to four different operating states. In the first operating state, both the injector 17 and the burner 19 are inactive, i.e. neither the injection of fuel into the exhaust gas stream nor the heating of the exhaust gas stream by the burner 19 is performed. In the second operating state, the injector 17 is inactive and the burner 19 is activated, that is, the exhaust gas stream is heated by the burner 19 but no fuel is injected. In the third operating state, the injector 17 is activated and the burner 19 is inactive, that is, fuel is supplied to the exhaust gas stream by the injector 17, but the exhaust gas stream is not heated by the burner 19. Not. In the fourth operating state, both the injector 17 and the burner 19 are operated, that is, both injection of fuel into the exhaust gas flow and heating of the exhaust gas flow by the burner 19 are performed simultaneously.

  Control of individual operating states of the regeneration module 23 is executed by means of the switching device 21 to which the regeneration module 23 is connected. The switching device 21 can have a simple electrical switching configuration using, for example, a strip-shaped bimetal for temperature determination. Alternatively, the switching device 21 may include a complicated integrated circuit. In the illustrated embodiment, the switching device 21 is configured as a separate control device arranged away from the reproduction module 23 and is connected to the reproduction module 23 via an electrical cable. As an alternative, the switching device 21 can also be configured as an additional component arranged directly on the reproduction module 23 or inside the reproduction module 23. In still another embodiment, the switching device 21 can be integrated into a combustion engine control device.

  The switching device 21 receives various input signals and controls the operation of the reproduction module 23 based on the input signals. In particular, the catalyst temperature signal 25 and the particulate filter deposition signal 27 are input to the switching device 21. However, various other inputs are provided for the means of determining whether regeneration of the particulate filter 11 is to be performed, whether the temperature of the catalyst 15 is above the light-off temperature, and whether fuel injection is required. A signal can also be assumed.

  When the particulate filter deposition signal 27 indicates that the particulate filter 11 should be regenerated, the switching device 21 refers to the catalyst temperature signal 25 and the temperature of the catalyst 15 is changed to the injected fuel. Confirm that the temperature is lower than the reaction temperature at which the exothermic reaction occurs. If so, the burner 19 is activated to heat the exhaust duct 13 with the catalyst 15. And the switching apparatus 21 confirms a catalyst temperature continuously based on the catalyst temperature signal 25 as needed. If the catalyst temperature exceeds the reaction temperature, the switching device 21 immediately activates the injector 17 if necessary to supply unburned liquid hydrocarbons into the exhaust gas stream. This liquid hydrocarbon causes an exothermic reaction in the catalyst 15, whereby heat is released and the catalyst temperature rises. The heating of the catalyst 15 by the fuel injection of the burner 19 and the injection device 17 is performed until reaching a predetermined threshold temperature after reaching the reaction temperature. After reaching the threshold temperature, the burner 19 is deactivated again by the switching device 21. The catalyst 15 and the particulate filter 11 disposed in the immediate vicinity thereof are heated by the exothermic reaction of the injected fuel, and a temperature sufficient to achieve incineration of soot-like fine particles in the particulate filter 11 and thus regeneration of the particulate filter 11. Until heated.

  In the illustrated embodiment, the regenerator is configured as a modular unit that includes both the injector 17 and the burner 19. Alternatively, the injection device 17 and the burner 19 can be realized as a single common component. Further, depending on the mode, the injection device 17 and the burner 19 may be configured as separate and independent devices, and both may be arranged apart from each other. For example, the injection device 17 can be realized by a fuel injection device provided for the operation of the combustion engine. In such a variant, fuel is supplied into the combustion chamber with a delay during the expansion stroke, so that the exhaust gas flow is at least partially unburned. Therefore, fuel injection is performed inside the engine, and it is not necessary to install another injection device 17.

  According to the regeneration module 23 described above, regeneration of the particulate filter 11 can be performed at any time regardless of the operating state of the exhaust system or the combustion engine. For example, immediately after the start of the combustion engine Even that is possible. In addition, a high-cost and large-occupied heating device for directly heating the particulate filter 11 to the soot incineration temperature is unnecessary. Furthermore, since fuel injection is only performed when it leads to the necessary result of raising the catalyst temperature above the light-off temperature, excessive fuel consumption is avoided. The regeneration concept of the present invention can be applied to various types of combustion engines in industrial plants and automotive fields.

DESCRIPTION OF SYMBOLS 11 ... Particulate filter 13 ... Exhaust duct 15 ... Catalyst 17 ... Injection device 19 ... Burner 21 ... Switching device 23 ... Regeneration module 25 ... Catalyst temperature signal 27 ... Particulate filter deposition signal

Claims (13)

An exhaust duct (13) for guiding a high-temperature exhaust gas flow from a combustion engine, particularly a diesel engine, and a catalyst (15), particularly an oxidation catalyst, incorporated in the exhaust duct (13) on the upstream side of the particulate filter (11). An apparatus for regenerating the particulate filter (11) in an exhaust system, the injector being capable of supplying the fuel, particularly hydrocarbon-containing fuel, to the exhaust gas stream in communication with a fuel reservoir to the exhaust system or the combustion engine In the configuration provided with (17),
A burner (19) capable of heating the catalyst (15) to a reaction temperature at which an exothermic reaction of the fuel occurs;
A switching device (21) for selectively switching the burner (19) and the injection device (17) to be activated or deactivated according to the operating state of the exhaust system and / or the combustion engine;
A playback apparatus comprising:   When the temperature of the catalyst (15) is lower than the reaction temperature and regeneration of the particulate filter (11) is necessary, the switching device (21) operates the burner (19) and injects as necessary. 2. The playback device according to claim 1, wherein the playback device is configured to operate the device (17).   The switching device (21) is configured to operate only the injection device (17) when the temperature of the catalyst (15) is higher than the reaction temperature and the particulate filter (11) needs to be regenerated. The reproducing apparatus according to claim 1 or 2, wherein   The switching device (21) is configured to deactivate the burner (19) again when the temperature of the catalyst (15) becomes higher than the reaction temperature. The reproducing | regenerating apparatus in any one of 1-3.   5. The playback device according to claim 1, wherein the playback device is configured as a modular unit (23).   6. Regenerator according to claim 5, characterized in that the injection device (17) is integrated in a modular unit (23).   The regenerator according to any one of claims 1 to 6, wherein the burner (19) and the injection device (17) are constituted by a common component. An exhaust system for a combustion engine, in particular a diesel engine,
An exhaust duct (13) for directing a hot exhaust gas flow from the combustion engine;
A particulate filter (11);
A catalyst (15), particularly an oxidation catalyst, incorporated in the exhaust duct (13) on the upstream side of the particulate filter (11);
With
The exhaust system or the combustion engine comprises an injection device (17) that communicates with a fuel reservoir and can supply the fuel, particularly a hydrocarbon-containing fuel, to an exhaust gas stream.
An exhaust system further comprising the regeneration device according to any one of claims 1 to 7. An exhaust duct (13) for guiding a high-temperature exhaust gas flow from a combustion engine, particularly a diesel engine, and a catalyst (15), particularly an oxidation catalyst, incorporated in the exhaust duct (13) on the upstream side of the particulate filter (11). A regeneration method for the particulate filter (11) in an exhaust system, the injection being capable of supplying the exhaust system or the combustion engine with fuel, in particular a hydrocarbon-containing fuel, in an exhaust gas stream in communication with a fuel reservoir In the configuration comprising the device (17),
A burner (19) capable of heating the catalyst (15) to a reaction temperature at which an exothermic reaction of the fuel occurs is provided;
Determine the operating status of the exhaust system and / or combustion engine,
A regeneration method comprising operating the burner (19) and / or the injection device (17) in accordance with the determined operating state when the particulate filter (11) is regenerated.   The regeneration method according to claim 9, characterized in that the temperature of the catalyst (15) is measured in order to determine the operating state of the exhaust system.   When the temperature of the catalyst (15) is lower than the reaction temperature and regeneration of the particulate filter (11) is necessary, the burner (19) is operated, and if necessary, the injection device (17) is operated. The reproduction method according to claim 9 or 10.   12. The injection device (17) alone is operated when the temperature of the catalyst (15) is higher than the reaction temperature and the particulate filter (11) needs to be regenerated. The playback method described in 1.   The regeneration method according to any one of claims 9 to 12, wherein the burner (19) is deactivated again when the temperature of the catalyst (15) becomes higher than the reaction temperature.

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